The purpose of this proposed research is to study the metabolism of naturally-occurring guanidinoxy compounds in mammals and to isolate and purify some of the enzymes involved. Specifically, the following investigations will be done: 1. Determination of the origin of hydroxyguanidine in mammals and the organ(s) in which synthesis occurs. 2. Further investigate the conversion of L-canavaninosuccinate to L-guanidinosuccinate and the conversion of L-canavanine to guanidine by mammalian liver preparations. 3. Purify the enzyme, hydroxyguanidine reductase and study its properties. 4. Investigate the possible synthesis L-canavanine by mammalian tissue. 5. Determine the metabolic fate in mammals of L-canaline, the deamidination product of L-canavanine.